Mitochondrial dosimeter

ABSTRACT

Mitochondrial mutations occur as a product of contact of a person with an environmental pollutant. Mitochondrial mutations are readily detectable in body fluids. Measurement of mitochondrial mutations in body fluids can be used as a dosimeter to monitor exposure to the environmental pollutant. Mitochondrial mutations can also be detected in cancer patients. Probes and primers containing mutant mitochondrial sequences can be used to monitor patient condition.

[0001] This application is a continuation-in-part of application Ser. No. 09/377,856 filed Aug. 20, 1999, which claims priority to provisional application Serial No. 60/097,307 filed Aug. 20, 1998. The disclosure of these prior applications is expressly incorporated herein.

[0002] The U.S. Government retains certain rights in this invention due to funding as provided by grant CA43460 awarded by the National Institutes of Health.

TECHNICAL FIELD OF THE INVENTION

[0003] This invention is related to the field of environmental toxicology, in particular to methods for measuring the effects of environmental toxins.

BACKGROUND OF THE INVENTION

[0004] The human mitochondrial (mt) genome is small (16.5 kb) and encodes 13 respiratory chain subunits, 22 tRNAs and two rRNAs. Mitochondrial DNA is present at extremely high levels (10³-10⁴ copies per cell) and the vast majority of these copies are identical (homoplasmic) at birth (1). Expression of the entire complement of mt genes is required to maintain proper function of the organelle, suggesting that even slight alterations in DNA sequences could have profound effects (2). It is generally accepted that mtDNA mutations are generated endogenously during oxidative phosphorylation via pathways involving reactive oxygen species (ROS), but they can also be generated by external carcinogens or environmental toxins. These mutations may accumulate partially because mitochondria lack protective histones and highly efficient DNA repair mechanisms as seen in the nucleus (3). Recently several mtDNA mutations were found specifically in human colorectal cancer (4).

SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide methods of monitoring exposure of a person to an environmental pollutant.

[0006] It is another object of the present invention to provide a kit for monitoring exposure of a person to environmental pollutants.

[0007] It is an object of the invention to provide methods to aid in the detection of cancer or metastasis.

[0008] It is an object of the invention to provide probes and primers for detecting mitochondrial mutations.

[0009] It is an object of the invention to provide a method to aid in detecting the presence of tumor cells in a patient.

[0010] These and other objects of the invention are achieved by providing one or more of the embodiments described below. In one embodiment a method is provided for monitoring exposure of a person to an environmental pollutant. The presence of one or more mutations in mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant is determined at two or more time points. The amounts of mutations in mtDNA at different time points are compared. The amount of mutations correlates with amount of exposure to the environmental pollutant.

[0011] According to another embodiment another method is provided for monitoring exposure of a person to an environmental pollutant. The prevalence of one or more mutations in mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant is measured. A measured prevalence of one or more mutations in mtDNA of greater than 1% indicates clonal expansion of cells which harbor the one or more mutations in the person.

[0012] According to still another embodiment of the invention a method is provided for monitoring exposure of a person to an environmental pollutant. One or more mutations in a D-loop of mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant are measured. The number of mutations in mtDNA correlates with exposure to the environmental pollutant.

[0013] According to yet another embodiment of the invention a kit is provided. The kit comprises one or more primers which hybridize to a mitochondrial D-loop for making a primer extension product. In addition, the kit contains written material identifying mutations which are found in the D-loop as a result of exposure to one or more environmental pollutants.

[0014] According to another embodiment of the invention an oligonucleotide probe is provided. The probe comprises a sequence of at least 10 contiguous nucleotides of a human mitochondrial genome. The probe can optionally contain at least 12, 14, 16, 18, 20, 22, 24, 26, or 30 such contiguous nucleotides. The oligonucleotide comprises a mutation selected from the group consisting of: a mutation selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793; C→T at nucleotide 10822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; T→C substitution at position 710; T→C substitution at position 1738; T→C substitution at position 3308; G→A substitution at position 8009; G→A substitution at position 14985; T→C substitution at position 15572; G→A substitution at position 9949; T→C substitution at position 10563; G→A substitution at position 6264; A insertion at position 12418; T→C substitution at position 1967; T→A substitution at position 2299; and G→A at nucleotide 3054.

[0015] According to another aspect of the invention an oligonucleotide primer is provided. It comprises a sequence of at least 10 contiguous nucleotides of a human mitochondrial genome. The primer can optionally contain at least 12, 14, 16, 18, 20, 22, 24, 26, or 30 such contiguous nucleotides. The oligonucleotide comprises a mutation selected from the group consisting of: a mutation selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793; C→T at nucleotide 10822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; T→C substitution at position 710; T→C substitution at position 1738; T→C substitution at position 3308; G→A substitution at position 8009; G→A substitution at position 14985; T→C substitution at position 15572; G→A substitution at position 9949; T→C substitution at position 10563; G→A substitution at position 6264; A insertion at position 12418; T→C substitution at position 1967; T→A substitution at position 2299; and G→A at nucleotide 3054.

[0016] Another aspect of the invention is a method to aid in detecting the presence of tumor cells in a patient. The presence of a single basepair mutation is detected in a mitochondrial genome of a cell sample of a patient. The mutation is found in a tumor of the patient but not in normal tissue of the patient. The tumor is not a colorectal tumor. The patient is identified as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.

[0017] Yet another embodiment of the invention is provided by another method to aid in detecting the presence of tumor cells in a patient. The presence of a mutation is determined in a D-loop of a mitochondrial genome of a cell sample of a patient. The mutation is found in a tumor of the patient but not in normal tissue of the patient. The patient is identified as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.

[0018] According to still another aspect of the invention a method is provided to aid in detecting the presence of tumor cells in a patient. The presence of a single basepair mutation is determined in a mitochondrial genome of a cell sample of a patient. The mutation is found in a cancer of the patient but not in normal tissue of the patient. The cancer is selected from the group of cancers consisting of: lung, head and neck, bladder, brain, breast, lymphoma, leukaemia, skin, prostate, stomach, pancreas, liver, ovarian, uterine, testicular, and bone. The patient is identified as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.

[0019] According to still another aspect of the invention a method is provided to aid in detecting the presence of tumor cells in a patient. The presence of a single basepair mutation is determined in a mitochondrial genome of a cell sample of a patient. The mutation is found in a tumor of the patient but not in normal tissue of the patient. The cancer is selected from the group of cancers consisting of: lung, head and neck, and bladder. The patient is identified as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.

[0020] Another embodiment of the invention provides a method to aid in detecting the presence of tumor cells in a patient. The presence of a mutation in a mitochondrial genome of a cell sample of a patient is determined. The mutation is selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793; C→T at nucleotide 10822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; T→C substitution at position 710; T→C substitution at position 1738; T→C substitution at position 3308; G→A substitution at position 8009; G→A substitution at position 14985; T→C substitution at position 15572; G→A substitution at position 9949; T→C substitution at position 10563; G→A substitution at position 6264; A insertion at position 12418; T→C substitution at position 1967; T→A substitution at position 2299; and G→A at nucleotide 3054. The patient is identified as having a tumor if one or more mutations are determined in the mitochondrial genome of the cell sample of the patient.

[0021] These and other embodiments provide the art with non-invasive tools for monitoring exposure to and the effects of environmental pollutants on the human body as well as early detection methods for cancer and metastasis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1. Schematic representation of a linearized mt genome. Hatched bars indicate the regions sequenced in this study and solid bars indicate the positions of tRNAs (transfer RNAs). rRNA=ribosomal RNA, ND=NADH dehydrogenase, COX=cytochrome c oxidase, Cyt b=cytochrome b, ATPase=ATP synthase.

[0023]FIG. 2. Sequence detection of mutated mtDNAs in samples from tumors and bodily fluids. (FIG. 2A) The mt mutation was analyzed by direct sequencing of the tumor (T), normal (N), and corresponding urine (U) DNAs of bladder cancer patient #799. The arrow indicates a single nucleotide change (G(A) at 2056 np in the 16S rRNA gene. (FIG. 2B and FIG. 2C) Examples of somatic mutations in head and neck cancers. Both mutations at 16172 np (B) and 10822 np (C) were detected from saliva (S) samples from patients #1680 and #1708, respectively. (FIG. 2D) Mutated mtDNA at 2664 np was not detected by sequence analysis in the paired BAL fluid (B), obtained from lung cancer patient #898.

[0024]FIG. 3. Oligonucleotide-mismatch ligation assay (22) to detect mtDNA mutations in BAL. The arrows identify mutated mt sequences at 12345 np within tRNA (FIG. 3A) and at 2664 np (FIG. 3B) within 16S rRNA in the tumor DNA. More dilute signals are seen in the corresponding BAL (B) samples with no detectable signal from the paired normal (N) tissue.

[0025]FIG. 4. Highly enriched mutated mtDNA in BAL samples from lung cancer patients. Oligonucleotide (oligo) specific hybridization detected ˜2000 plaques containing WT p53 clones in the BAL from patient #1113, and only two plaques (2/2000=0.1%) with the p53 gene mutation (FIG. 4A) were found in the primary tumor. The same BAL sample demonstrated a much greater enrichment of mutated mtDNA; 445 plaques contained mtDNA mutations (FIG. 4A) at 16159 np (445/2000=22.3%; 220-fold) compared to approximately 1500 WT clones. A similar enrichment was seen in patient #1140 where oligo specific hybridization detected 12 p53 mutant plaques among 437 WT clones (2.7%, FIG. 4B), while mutant mtDNA at 16380 np (FIG. 4B) represented over 50% of the plaques (52.3%, 460/880; 19-fold) amplified from mtDNA.

[0026]FIG. 5. Pseudoclonal selection of mtDNA. A mitochondrial genome gains some replicative advantage due to a somatic mutation (such as in the D-loop region), leading to a dominant mitochondrial genotype (step 1). This mitochondrion can gain additional replicative advantage through nuclear influences: for example, a mutated sequence gains a higher binding affinity to nuclear-encoded mitochondrial trans-acting factors (step 2). Due to its stochastic segregation together with the clonal expansion of a neoplastic cell driven by nuclear mutations, mutated mitochondria overtake the entire population of tumor cells (step 3).

BRIEF DESCRIPTION OF THE TABLES

[0027] Table 1 provides a summary of mutations in mitochondria of colorectal tumors.

[0028] Table 2 provides a summary of mutations in mitochondria of bladder, lung, head and neck tumors.

[0029] Table 3 provides a summary of new polymorphisms in mitochondria of bladder, lung, head and neck tumors.

DETAILED DESCRIPTION

[0030] It is a discovery of the present inventors that mitochondrial DNA mutations can be monitored non-invasively and sensitively and used as an indicator of environmental pollutants. It is shown below that these mutations are more prevalent in body samples than nuclear mutations, and thus are detected more sensitively. Mitochondrial mutations can be monitored over time to detect changes in the amount of exposure to pollutants. In addition, the prevalence of the mitochondrial mutation in the sample indicates whether clonal proliferation has occurred. Finally, the D-loop has been identified as a hotspot of mutations within the mitochondrial genome.

[0031] Mitochondrial mutations are determined with reference to wild-type human mitochondrial sequence. Sequence information can be found at the website http://www.gen.emory.edu/mitomap.html and at SEQ ID NO: 1. However, some differences between a sample sequence and a documented wild-type sequence can be polymorphisms, not mutations. Table 3 provides a number of new polymorphisms. Other polymorphisms can be found in references 2 and 8. Polymorphisms can be distinguished from somatic mutations by comparing the sequence in the sample to the corresponding sequence in a normal body tissue of the same person. If the same variant sequence is found in the sample as in the normal body tissue it is a polymorphism. Normal tissues can be paraffin-embedded. It has been found by the present inventors that mitochondrial DNA which is paraffin-embedded remains more highly intact and amplifiable than genomic DNA. Amplifiable regions of mitochondrial DNA may be from 10 bp to about 4 kb, desirably 2 kb to 4 kb or 10 bp to about 2 kb. Other suitable sources of reference mtDNA are blood, serum, or plasma of the human being tested.

[0032] Suitable bodily fluids for testing according to the present invention include saliva, sputum, urine, and bronchoalveolar lavage (BAL). These can be collected as is known in the art. People who are prime candidates for testing and supplying such bodily fluids are those who have been episodically, periodically or chronically exposed to environmental pollutants. These include without limitation cigarette smoke, biological toxins, such as aflatoxin, cholera toxin, and botulinum toxin, radiation including UV irradiation, industrial wastes, chemicals, water-borne or air-borne pollutants, and drugs. The environmental pollutant can be known, suspected, or unidentified, as the assay depends on the effect and not on the identity of the pollutant.

[0033] The inventors have found that there are certain characteristics of the mutations which are found in mitochondrial DNA. Many mutations are found in sequences which do not encode proteins. These include the D-loop region (i.e., nucleotides 16024-526), the 16S RNA gene, and the tRNA genes.

[0034] Furthermore, even where the mutations do occur in protein coding regions, they often result in silent mutations which do not affect the encoded amino acids. Other regions frequently affected include the genes for NADH dehydrogenase 4, NADH dehydrogenase 3, NADH dehydrogenase 5, and cytochrome B.

[0035] Mutation detection can be done according to any methodology which is known in the art for determining mutations. These include without limitation, nucleotide sequencing, hybridization, amplification, PCR, oligonucleotide mismatch ligation assays, primer extension assays, heteroduplex analysis, allele-specific amplification, allele-specific primer extension, SCCP, DGGE, mass spectroscopy, high pressure liquid chromatography, and combinations of these techniques.

[0036] Prevalence of a particular mutation according to the present invention can be used to monitor clonal expansion. Mutations which are present in greater than 1% of the mitochondrial DNA present in a sample have may have conferred a growth advantage on the cells harboring them. Even if no growth advantage is conferred by the mutation itself, the mutation serves as a marker for a clone which is expanding relative to the population of cells in the sample. Clonal expansion can be measured over time to monitor the growth of the clone or to monitor the efficacy of anti-proliferative agents which can be considered environmental pollutants, according to the present invention.

[0037] The inventors have also found that the presence of subtle mutations in the mitochondrial genome can be used as a means to trace the presence, spread, metastasis, growth, or recurrence of a tumor in a patient. Such subtle mutations include single basepair substitutions, single basepair insertions, and single basepair deletions. Single basepair substitutions can be either transitions or transversions, although the former are more frequent. Detection of such mutations can be useful to screen for the initial appearance of a tumor as well as the recurrence of a previously identified tumor. The methods are particularly suited to monitor anti-cancer therapy, recurrence, metastasis, and completeness of surgical removals.

[0038] A single basepair substitution is the substitution of a single nucleotide base with a different nucleotide base at the same position, with the corresponding substitution of the complementary base on the other strand of the DNA. While any single basepair substitution is conceivable within the scope of the invention, the most frequently encountered substitutions are those which are consistent with endogenous oxidative damage, such as T to C or G to A transitions, or which are consistent with a variety of external carcinogens which cause a variety of types of mutations. The mutations can appear in protein coding or non-coding regions or in regions which encode ribosomal or transfer RNAs.

[0039] The homoplasmic or near homoplasmic property of most mutant mitochondrial genomes from tumors permits the ready detection of such mutations within a sample of mitochondrial DNA from a patient. Homoplasmic mutations are those which appear in essentially all of the copies of the mitochondrial genome within a given cell or tissue. However, heteroplasmic mutations, which are those appearing in only a fraction of the mitochondrial genomes of a cell or tissue, are also suitable for use with the invention.

[0040] Any cell sample can be tested from a patient who has cancer or is suspected of having cancer. Suitable cell samples include, but are not limited to, tissue from a growth suspected or known to be cancerous, tissue adjacent to a resection of a tumor, and tissue distant from the site of a tumor, such as lymph nodes which are suspected of bearing metastatic cells. Cells can also be obtained from bodily fluids or secretions, e.g., blood, urine, sputum, saliva, or feces, which may contain cancerous cells or metastatic cells. Cell samples can also be collected from other bodily secretions and tissues as is known in the art. A cell sample can be collected from suspected or known cancerous tissue or from bodily fluids or secretions harboring cancer cells as well as from suspected or known normal tissue or bodily fluids or secretions harboring normal cells.

[0041] In order to detect mutations of the mitochondrial genome from a cell sample of a patient, mitochondrial DNA can be isolated from the cell sample using any method known in the art. One way of identifying subtle mutations involves sequencing the mitochondrial DNA. This can be done according to any method known in the art. For example, isolated mitochondrial DNA can be cleaved using endonucleases into overlapping fragments of appropriate size for sequencing, e.g., about 1-3 kilobases in length, followed by polymerase chain reaction (PCR) amplification and sequencing of the fragments. Examples of DNA sequencing methods are found in Brumley, R. L. Jr., and Smith, L. M., 1991, Rapid DNA sequencing by horizontal ultrathin gel electrophoresis, Nucleic Acids Res. 19:4121-4126 and Luckey, J. A., Drossman, H., Kostihka, T.; and Smith, L. M., 1993, High-speed DNA sequencing by capillary gel electrophoresis, Methods Enzymol. 218:154-172. Amplification methods such as PCR can be applied to samples as small as a single cell and still yield sufficient DNA for complete sequence analysis. The combined use of PCR and sequencing of mitochondrial DNA is described in Hopgood, R., Sullivan, K. M., and Gill, P., 1992, Strategies for automated sequencing of human mitochondrial DNA directly from PCR products, Biotechniques 13:82-92 and Tanaka, M., Hayakawa, M., and Ozawa, T., 1996, Automated sequencing of mitochondrial DNA, Methods Enzymol. 264:407-21.

[0042] Mutations can first be identified by comparison to sequences present in public databases for human mitochondrial DNA, e.g., at http://www.gen.emory.edu/mitomap.html and at SEQ ID NO: 1. Any single basepair substitution identified in the sample DNA compared to a normal sequence from a database can be confirmed as being a somatic mutation as opposed to a polymorphic variant by comparing the sample mitochondrial DNA or sequences obtained from it to control cell mitochondrial DNA from the same individual or sequences obtained from it. Control cells are isolated from other apparently normal tissues, i.e., tissues which are phenotypically normal and devoid of any visible, histological, or immunological characteristics of cancer tissue. A difference between the sample and the control identifies a somatic mutation which is associated with the tumor.

[0043] An alternative to serially sequencing the entire mitochondrial genome in order to identify a single basepair substitution is to use hybridization of the mitochondrial DNA to an array of oligonucleotides. Hybridization techniques are available in the art which can rapidly identify mutations by comparing the hybridization of the sample to matched and mismatched sequences which are based on the human mitochondrial genome. Such an array can be as simple as two oligonucleotide probes, one of whose sequence matches the wild-type or mutant region containing the single base substitution (matched probe) and another whose sequence includes a single mismatched base (mismatch control probe). If the sample DNA hybridizes to the matched probe but not the mismatched probe, it is identified as having the same sequence as the matched probe. Larger arrays containing thousands of such matched/mismatched pairs of probes on a glass slide or microchip (“microarrays” or “gene chips”) are available which are capable of sequencing the entire mitochondrial genome very quickly. Such arrays are commercially available. Review articles describing the use of microarrays in genome and DNA sequence analysis and links to their commercial suppliers are available at www.gene-chips.com.

[0044] The invention can be used to screen patients suspected of having cancer for the presence of tumor cells. A cell sample is first obtained from a suspected tumor of the patient, or is obtained from another source such as blood or lymph tissue, for example, if metastasis is suspected. The cell sample is tested to determine the presence of a single basepair mutation in mitochondrial DNA from the cell sample using the techniques outlined above. Optionally, a cell sample from normal, non-cancerous cells or tissue of the patient is also obtained and is tested for the presence or absence of a single basepair mutation in mitochondrial DNA. If a single basepair mutation is determined which is not present in a cell sample from normal tissue of the patient, then the mutation is a somatic mutation and the presence of tumor cells in the patient is indicated. If one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient, then the patient is identified as having a tumor. As in any diagnostic technique for cancer, to confirm or extend the diagnosis, further diagnostic techniques may be warranted. For example, conventional histological examination of a biopsy specimen can be performed to detect the presence of tumor cells, or analysis of a tumor-specific antigen in a blood or tissue sample can be performed.

[0045] The method outlined above can be practiced either in the situation where the somatic mutation is previously known or previously unknown. The method can be practiced even in the absence of prior knowledge about any particular somatic mutation. The method can also be carried out subsequent to the discovery of a somatic mutation in a mitochondrial genome of a cell of the patient or of another patient. In this case, a previous association of the somatic mutation with the presence of a tumor in the patient or in another patient strongly indicates the presence of tumor cells in the patient. It may also indicate the recurrence of a tumor or the incomplete prior removal of cancerous tissue from the patient.

[0046] The effectiveness of therapy can be evaluated when a tumor has already been identified and found to contain a single basepair substitution in the mitochondrial genome. Once a single basepair mutation has been identified in the mitochondrial DNA of a tumor of the patient, further tumor cells can be detected in tissue surrounding a resection or at other sites, if metastasis has occurred. Using the methods outlined above, the recurrence of the tumor or its incomplete removal can be assessed. Similarly, if a tumor has been treated using a non-surgical method such as chemotherapy or radiation, then the success of the therapy can be evaluated at later times by repeating the analysis. The step for determining the presence of a single basepair mutation in a mitochondrial genome of a cell sample of a patient can be performed 1, 2, 3, 4, 5, 6, 8, 10, or more times in order to monitor the development or regression of a tumor or to monitor the progress or lack of progress of therapy undertaken to eliminate the tumor.

[0047] Upon repeated analyses, the step for determining the presence of a single basepair mutation is simplified, because only a well defined and limited region of the genome need be sequenced. Using the hybridization method, for example, it is possible to evaluate the presence of the mutation with only a single matched/mismatched pair of oligonucleotide probes in the array. In the event that a mixture of genotypes is observed, it is possible to obtain quantitative information about the relative amount of each mitochondrial genotype using techniques known to the art, e.g., hybridization. Quantitative analysis can reveal changes in the relative proportion of tumor to normal cells in a tissue over time or in response to therapy.

[0048] The following examples are provided to demonstrate certain aspects of the invention but they do not define the scope of the invention.

EXAMPLE 1

[0049] This example demonstrates detection of mt mutations in tissue samples.

[0050] To determine whether mt mutations could be identified in cancer other than colorectal cancer, we studied primary bladder (n=14), head and neck (n=13), and lung (n=14) tumors (5). Eighty percent of the mt genome of all the primary tumor samples was PCR-amplified (6) and sequenced manually (FIG. 1). Tumor mtDNA was compared to mtDNA from paired blood samples in all cases, and mtDNA from corresponding normal tissue when available (7). Of the 292 sequence variants detected, 196 were previously recorded polymorphisms (2, 8), while 57 were novel polymorphisms (Table 3). The remaining 39 variants were acquired (somatic) mutations identified in 64% (9/14) of the bladder cancer, 46% (6/13) of the head and neck cancer, and 43% (6/14) of the lung cancer patients (Table 2). Most of these mutations were T-to-C and G-to-A base transitions, indicating possible exposure to ROS-derived mutagens (9). Similar to the previous observation by Polyak et al. (Table 1; 4), the majority of the somatic mutations identified here were also homoplasmic in nature. In addition, several of the bladder and head and neck cancers studied here (Table 2) had multiple mutations implying possible accumulation of mtDNA damage.

[0051] In the bladder tumors, mutation hot spots were primarily in the NADH dehydrogenase subunit 4 (ND4) gene (35%), and in the displacement-loop (D-loop) region (30%). The D-loop region is a critical site for both replication and expression of the mt genome since it contains the leading-strand origin of replication and the major promoters for transcription (10). Many (73%) of the mutations identified within protein-coding regions were silent, except for a (Val→Ala) substitution in the NADH dehydrogenase subunit 3 (ND3) and a 7-amino-acid deletion in cytochrome b (Cyt b). The D-loop region was also commonly mutated in head and neck cancer (67%). Two of the head and neck tumors (22%) contained mutations in the ND4 gene at nucleotide pairs (nps) 10822 and 11150, resulting in amino acid substitutions of Thr→Met and Ala→Thr, respectively. A similar tendency was observed in lung cancers, demonstrating a high concentration of mutations in the D-loop region (70%).

EXAMPLE 2

[0052] This example demonstrates detection of mt mutations in bodily fluids.

[0053] We hypothesized that the homoplasmic nature of these mutations would make them readily detectable in paired bodily fluids. To test this, we extracted and directly amplified mtDNA from urine samples from patients diagnosed with bladder cancer. All three corresponding urine samples available in this study contained the mutant mtDNA derived from tumor tissues. For example, the mtDNA from a urine sample of bladder cancer patient #799 showed the same nucleotide transition (G→A) as seen in the tumor (FIG. 2A). In all cases, the urine sample contained a relatively pure population of tumor-derived mtDNA, comparable to that of the micro-dissected tumor sample. Consistent with this observation, saliva samples obtained from head and neck cancer patients contained no detectable wild-type (WT) signals (FIG. 2B, and 2C). By sequence analysis alone, we were able to detect mtDNA mutations in 67% (6/9) of saliva samples from head and neck cancer patients. In lung cancer cases, we were initially unable to identify mutant bands from paired bronchoalveolar lavage (BAL) fluids because of the significant dilution of neoplastic cells in BAL fluid (11), (FIG. 2D). We, thus, applied a more sensitive oligonucleotide-mismatch ligation assay to detect mutated mtDNA. As shown in FIG. 3A and 3B, both lung cancer mutations (arrows) were confirmed in tumor mtDNA with more dilute signals in the corresponding BAL samples, and no signal in the corresponding normal tissues. Again, we detected the majority of mtDNA mutations (8/10) in BAL fluids with the exception of two cases where the ligation assays were not feasible due to the sequence compositions (16183 and 302 nps) adjacent to the mutations.

EXAMPLE 3

[0054] This example demonstrates the enrichment of mitochondrial mutant DNA in samples relative to nuclear mutant DNA.

[0055] To quantitate this neoplastic DNA enrichment, we compared the abundance of mt gene mutations to that of nuclear-encoded p53 mutations in bodily fluids using a quantitative plaque assay. Nuclear and mt fragments that contained a mutated sequence were PCR-amplified and cloned for plaque hybridization (12). Two BAL samples from lung cancer patients were chosen for analysis because they had mutations in both the mt and nuclear genomes. For p53 mutations, the percentages of neoplastic cells among normal cells for patients #1113 and #1140 were 0.1 and 3.0%, respectively. Remarkably, the abundance of the corresponding mutated mtDNA (MT) was 22% and 52% when compared to the wild-type (WT) mt sequence (FIG. 4). This enrichment of mtDNA is presumably due to the homoplasmic nature of these mutations and the high copy number of mt genomes in cancer cells. Enrichment was further suggested by our observations in head and neck paraffin samples where we were able to PCR-amplify 2-3 kb fragments of mtDNA, whereas we were unable to amplify nuclear p53 gene fragments of over 300 bp.

[0056] A role for mitochondria in tumorigenesis was implicated when tumor cells were found to have an impaired respiratory system and high glycolytic activity (13,14). Recent findings elucidating the role of mitochondria in apoptosis (15) and the high incidence of mtDNA mutations in colon cancer (4) further support the original hypothesis of mitochondrial participation in the initiation and progression of cancer. Although further investigation is needed to define the functional significance of mt mutations, our data clearly show that those mutations are frequent and present at high levels in all of the tumor types examined.

[0057] The homoplasmic nature of the mutated mitochondria remains puzzling. It is estimated that each cell contains several hundred-to-thousands of mitochondria and that each mitochondrion contains 1-10 genomes (16). Conceivably, certain mutated mtDNAs may gain a significant replicative advantage. For example, mutations in the D-loop regulatory region might alter the rate of DNA replication by modifying the binding affinity of important trans-acting factors. Mitochondria that undergo the most rapid replication are likely to acquire more DNA damage, leading to an accumulation of mutational events. Although the mechanism may vary for other mutations (such as silent mutations in the ND4 gene), the accumulation of a particular mtDNA mutation may become more apparent during neoplastic transformation. Even subtle mtDNA mutations may also gain significant replicative advantage, perhaps through interactions with important nuclear factors. Homoplasmic transformation of mtDNA was observed in small populations of cells in other non-neoplastic, but diseased tissues (17), sometimes associated with aging (18). We hypothesize that, in contrast to classic clonal expansion, the process may occur as “pseudoclonal” selection where stochastic segregation of mitochondria (16) together with neoplastic clonal expansion driven by nuclear mutations lead to a homogeneous population of a previously “altered” mitochondrion (FIG. 5).

[0058] The large number of mt polymorphisms identified here and elsewhere (2) likely reflects the high mutation rate of mtDNA, which is thought to be caused mainly by high levels of ROS (19). In agreement with this, our data imply that constitutive hypervariable areas such as the D-loop region represent somatic mutational hot spots. As further mutations are tabulated in primary V tumors, DNA-chip technology can be harnessed to develop high-throughput analyses with sufficient sensitivity (20, 21). Due to its high copy number, mtDNA may provide a distinct advantage over other nuclear genome based methods for cancer and environmental pollutant detection.

Literature Cited

[0059] 1. R. N. Lightowlers, P. F. Chinnery, D. M. Turnbull, N. Howell, Trends Genet 13, 450 (1997).

[0060] 2. MITOMAP: A Human Mitochondrial Genome Database. Center for Molecular Medicine, Emory University, Atlanta, Ga., USA. http://www.gen.emory.edu/mitomap.html

[0061] 3. D. L. Croteau and V. A. Bohr, J. Biol. Chem. 272, 25409 (1997).

[0062] 4. K. Polyak et al., Nature Genet. 20, 291 (1998).

[0063] 5. Paired normal and tumor specimens along with blood and bodily fluids were collected following surgical resections with prior consent from patients in The Johns Hopkins University Hospital. Tumor specimens were frozen and micro-dissected on a cryostat so that the tumor samples contained greater than 70% neoplastic cells. DNA from tumor sections was digested with 1% SDS/Proteinase K, extracted by phenol-chloroform, and ethanol precipitated. Control DNA from peripheral lymphocytes, matched normal tissues, from urine, saliva, and BAL fluid were processed in the same manner as described in (11).

[0064] 6. Mitochondrial DNAs were amplified using overlapping primers (4) in PCR buffer containing 6% DMSO. Approximately 5-20 ng of genomic DNA was subjected to the step-down PCR protocol: 94° C. 30 sec, 64° C. 1 min, 70° C. 3 min, 3 cycles, 94° C. 30 sec, 61° C. 1 min, 70° C. 3 min, 3 cycles, 94° C. 30 sec, 58° C. 1 min, 70° C. 3.5 min 15 cycles, 94° C. 30 sec, 1 min, 70° C. 3.5 min, 15 cycles, and a final extension at 70° C. for 5 min. PCR products were gel-purified using a Qiagen gel extraction kit (Qiagen) and sequence reactions were performed with Thermosequenase (Perkin-Elmer) using the cycle conditions (95° C. 30 sec, 52° C. 1 min, and 70° C. 1 min for 25 cycles).

[0065] 7. Corresponding normal tissues from 4 patients (#874, #915, #1684, and #1678) were available and DNA was extracted from paraffin samples as described previously (9).

[0066] 8. R. M. Andrew et al., Nature Genet. 23 147, (1999)

[0067] 9. J. Cadet, M. Berger, T. Douki, J. L. Ravanat, Rev. Physiol. Biochem. Pharmacol. 131, 1 (1997).

[0068] 8. J. W. Taanman, Biochimica. et. Biophysica. Acta. 1410, 103 (1999).

[0069] 9. S. A. Ahrendt et al., J. Natl. Cancer Inst. 91, 332 (1999).

[0070] 10. Subcloning of PCR fragments into phage vector was performed according to the manufacturer's instructions (Stratagene). Titered plaques were plated and subjected to hybridization using tetramethylammonium chloride (TMAC) as a solvent. Positive signals were confirmed by secondary screenings. Oligonucleotides (Oligos) used for this assay were as follows; for patient #1113, p53 and mtDNA sequence alterations were detected using oligos containing either WT-(p53: 5′-GTATTTGGATGTCAGAAACACTT-3′ (SEQ ID NO: 2)/mtDNA: 5′-ACTTCAGGGTCATAAAGCC-3′ (SEQ ID NO: 3)) or MT (p53: 5′-GTATTTGGATGTCAGAAACACTT-3′ (SEQ ID NO: 4)/mtDNA:5′-ACTTCAGGGCCATAAAGCC-3′(SEQ ID NO: 5)) sequences, respectively. For patient #1140, oligos 5′-ACCCGCGTCCGCGCCATGGCC-3′ (SEQ ID NO: 6) and 5′-ACCCGCGTCCTCGCCATGGCC-3′ (SEQ ID NO: 7) were used to detect WT and MT sequences, respectively.

[0071] 11. O. Warburg, Science 123, 309 (1956).

[0072] 12. J. W. Shay and H. Werbin, Mut. Res. 186, 149 (1987).

[0073] 13. D. R. Green and J. C. Reed, Science 281, 1309 (1999).

[0074] 14. D. C. Wallace, Annu. Rev. Biochem. 61, 1175 (1992).

[0075] 15. D. C. Wallace, Proc. Natl. Acad. Sci. USA 91, 8746 (1994).

[0076] 16. K. Khrapko et al., N.A.R. 27, 2434 (1999).

[0077] 17. C. Richter, J. W. Park, B. N. Ames, Proc. Natl. Acad. Sci. U S A 17, 6465 (1988).

[0078] 18. M. Chee et al., Science 274, 610 (1996).

[0079] 19. S. A. Ahrendt et al., Proc. Natl. Acad. Sci. USA 96, 7382 (1999).

[0080] 20. Fragments containing mutations were PCR-amplified and then ethanol precipitated. For each mutation, discriminating oligonucleotides that contained the mutated base at the 3′ end were designed (TAACCATA-3′ (SEQ ID NO: 8) for patient #915 and TCTCTTACC-3′ (SEQ ID NO: 9) for patient #898). Immediately adjacent [³²P] end-labeled 3′ sequences (5′-CACACTACTA-3′ (SEQ ID NO: 10) for patient #915 and 5′-TTTAACCAG-3′ (SEQ ID NO: 11) for patient #898) were used as substrate together with discriminating oligonucleotides for the ligation reaction. After a denaturing step of 95° C. for 5′, the reactions were incubated for 1 hr at 37° in the presence of T4 DNA ligase (Life Technologies), in a buffer containing 50 mM Tris-Cl, 10 mM MgCl₂, 150 mM NaCl, 1 mM Spermidine, 1 mM ATP, 5 mM DTT, and analyzed on denatured 12% polyacrylamide gels. [Jen et al., Cancer Res. 54, 5523 (1994)]. TABLE 1 Summary of mtDNA mutations Tumor* Position DNA Protein Gene C478 710 T → C — 12S rRNA ″ 1738 T → C — 16S rRNA ″ 3308 T → C M1T ND1 V429 8009 G → A V142M COX subunit II ″ 14985 G → A R80H CYT b ″ 15572 T → C F276L CYT b V441 9949 G → A V2481 COX subunit III V456 10563 T → C C32R ND4L V425 6264 G → A G121trun COX subunit I ″ 12418 insA K28frameshift ND5 V451 1967 T ∝3 C — 16S rRNA V410 2299 T → A — 16S rRNA

[0081] TABLE 2 Summary of mitochondrial mutations in primary tumors. Patient# Location Sequence Protein Gene Bladder Cancer (9/14, 57%) 1124 114 T → C N/C D-loop 580 302 Del C N/C D-loop 580 386 C ∝3 A N/C D-loop 799 2058 G → A N/C 16SrRNA 716 2445 T ∝3 C N/C 16SrRNA 1127 3054 G → A N/C 16SrRNA 884 10071 T → C L-L ND3 884 10321 T → C V-A ND3 884 10792 A → G L-L ND4 884 10793 C → T L-L ND4 899 10822 C → T H-H ND4 716 10978 A → G L-L ND4 870 11065 A → G L-L ND4 870 11518 G → A L-L ND4 884 12049 C → T F-F ND4 874 12519 T → C V-V ND5 580 15642 Del 7aa Cyt b 899 16189 Ins T N/A D-loop 1124 16265 A → C N/A D-loop 1127 16532 A → T N/A D-loop Lung Cancer (6/15, 40%) 1174 150 C → T N/C D-loop 1174 195 T → C N/C D-loop 902 302 Del C N/C D-loop 898 2664 T → C N/C 16sRNA 915 5521 G → A N/C tRNATrp 915 12345 G → A N/C tRNALeu 915 16183 C → A N/C D-loop 915 16187 C ∝3 T N/C D-loop 1113 16519 T → C N/C D-loop 1140 16380 G → A N/C D-loop Head and Neck Cancer (6/13, 46%) 1637 75 G → A N/C D-loop 1680 302 Ins C N/C D-loop 1565 514 Ins CG N/C D-loop 1708 10966 T → C T ∝3 T ND 4 1678 11150 G ∝3 A A ∝3 T ND 4 1680 16172 T ∝3 C N/C D-loop 1680 16292 C → T N/C D-loop 1680 16300 A ∝3 G N/C D-loop

[0082] TABLE 3 New mtDNA polymorphisms (n = 57) found in this study. Sequence change Tumor Position Gene DNA Protein B 633 tRNA Phe A → G — B 723 12S rRNA A → G — B, L, HNC 1738 16S rRNA T → C — B 1872 16S rRNA T → C — L 2308 16S rRNA A → G — B, L 2395 16S rRNA Del A — HNC 2712 16S rRNA G → A — HNC 2758 16S rRNA G → A — L 2765 16S rRNA A → G — HNC 2768 16S rRNA A → C — HNC 3148 16S rRNA C → T — B, L, HNC 3308 ND1 T → C M → T B 4823 ND2 T → C V → V B 4917 ND2 A → G N → D B 5509 ND2 T → C L → S B 5567 tRNA Trp T → C — B 5580 NCN T → C — B 5899 NCN Del C — B 6149 CoxI A → G L → L B 6150 CoxI G → A V → I B 6253 CoxI T → C M → T B 6261 CoxI G → A A → T B 6302 CoxI A → G A → A B 7966 CoxII C → T F → F B 8037 CoxII G → A R → H B 8248 CoxII A → G M → M B 8655 ATPase6 C → T I → I B 8877 ATPase6 T → C F → F B 9072 ATPase6 A → G S → S B 9093 ATPase6 A → G T → T B 9266 CoxIII G → A G → G B 9497 CoxIII T → C F → F L 10321 ND3 T → C V → A HNC 10403 ND3 A → G E → E B, L, HNC 10688 ND 4L G → A V → V B, L, HNC 10810 ND 4 T → C L → L B 11164 ND 4 A → G R → R L 11257 ND 4 C → T Y → Y HNC 11339 ND 4 T → C L → L L 11899 ND 4 T → C S → S L 12519 ND 5 T → C V → V B, L 14769 Cyt b A → G N → S B 14992 Cyt b T → C L → L L 15139 Cyt b T → C Y → Y L 15514 Cyt b T → C Y → Y L 15586 Cyt b T → C I → I B 15601 Cyt b T → C P → P L 15670 Cyt b T → C H → H B 15672 Cyt b T → C M → T B 15787 Cyt b T → C F → F HNC 15941 tRNA Thr T → C — L 15942 tRNA Thr T → C — B 16130 D-Loop G → A — L 16170 D-Loop A → G — L 16204 D-Loop G → C — L 16211 D-Loop C → T — B 16225 D-Loop C → T —

[0083]

1 11 1 16568 DNA Homo sapiens 1 gatcacaggt ctatcaccct attaaccact cacgggagct ctccatgcat ttggtatttt 60 cgtctggggg gtatgcacgc gatagcattg cgagacgctg gagccggagc accctatgtc 120 gcagtatctg tctttgattc ctgcctcatc ctattattta tcgcacctac gttcaatatt 180 acaggcgaac atacttacta aagtgtgtta attaattaat gcttgtagga cataataata 240 acaattgaat gtctgcacag ccactttcca cacagacatc ataacaaaaa atttccacca 300 aaccccccct cccccgcttc tggccacagc acttaaacac atctctgcca aaccccaaaa 360 acaaagaacc ctaacaccag cctaaccaga tttcaaattt tatcttttgg cggtatgcac 420 ttttaacagt caccccccaa ctaacacatt attttcccct cccactccca tactactaat 480 ctcatcaata caacccccgc ccatcctacc cagcacacac acaccgctgc taaccccata 540 ccccgaacca accaaacccc aaagacaccc cccacagttt atgtagctta cctcctcaaa 600 gcaatacact gaaaatgttt agacgggctc acatcacccc ataaacaaat aggtttggtc 660 ctagcctttc tattagctct tagtaagatt acacatgcaa gcatccccgt tccagtgagt 720 tcaccctcta aatcaccacg atcaaaagga acaagcatca agcacgcagc aatgcagctc 780 aaaacgctta gcctagccac acccccacgg gaaacagcag tgattaacct ttagcaataa 840 acgaaagttt aactaagcta tactaacccc agggttggtc aatttcgtgc cagccaccgc 900 ggtcacacga ttaacccaag tcaatagaag ccggcgtaaa gagtgtttta gatcaccccc 960 tccccaataa agctaaaact cacctgagtt gtaaaaaact ccagttgaca caaaatagac 1020 tacgaaagtg gctttaacat atctgaacac acaatagcta agacccaaac tgggattaga 1080 taccccacta tgcttagccc taaacctcaa cagttaaatc aacaaaactg ctcgccagaa 1140 cactacgagc cacagcttaa aactcaaagg acctggcggt gcttcatatc cctctagagg 1200 agcctgttct gtaatcgata aaccccgatc aacctcacca cctcttgctc agcctatata 1260 ccgccatctt cagcaaaccc tgatgaaggc tacaaagtaa gcgcaagtac ccacgtaaag 1320 acgttaggtc aaggtgtagc ccatgaggtg gcaagaaatg ggctacattt tctaccccag 1380 aaaactacga tagcccttat gaaacttaag ggtcgaaggt ggatttagca gtaaactaag 1440 agtagagtgc ttagttgaac agggccctga agcgcgtaca caccgcccgt caccctcctc 1500 aagtatactt caaaggacat ttaactaaaa cccctacgca tttatataga ggagacaagt 1560 cgtaacatgg taagtgtact ggaaagtgca cttggacgaa ccagagtgta gcttaacaca 1620 aagcacccaa cttacactta ggagatttca acttaacttg accgctctga gctaaaccta 1680 gccccaaacc cactccacct tactaccaga caaccttagc caaaccattt acccaaataa 1740 agtataggcg atagaaattg aaacctggcg caatagatat agtaccgcaa gggaaagatg 1800 aaaaattata accaagcata atatagcaag gactaacccc tataccttct gcataatgaa 1860 ttaactagaa ataactttgc aaggagagcc aaagctaaga cccccgaaac cagacgagct 1920 acctaagaac agctaaaaga gcacacccgt ctatgtagca aaatagtggg aagatttata 1980 ggtagaggcg acaaacctac cgagcctggt gatagctggt tgtccaagat agaatcttag 2040 ttcaacttta aatttgccca cagaaccctc taaatcccct tgtaaattta actgttagtc 2100 caaagaggaa cagctctttg gacactagga aaaaaccttg tagagagagt aaaaaattta 2160 acacccatag taggcctaaa agcagccacc aattaagaaa gcgttcaagc tcaacaccca 2220 ctacctaaaa aatcccaaac atataactga actcctcaca cccaattgga ccaatctatc 2280 accctataga agaactaatg ttagtataag taacatgaaa acattctcct ccgcataagc 2340 ctgcgtcaga ttaaaacact gaactgacaa ttaacagccc aatatctaca atcaaccaac 2400 aagtcattat taccctcact gtcaacccaa cacaggcatg ctcataagga aaggttaaaa 2460 aaagtaaaag gaactcggca aatcttaccc cgcctgttta ccaaaaacat cacctctagc 2520 atcaccagta ttagaggcac cgcctgccca gtgacacatg tttaacggcc gcggtaccct 2580 aaccgtgcaa aggtagcata atcacttgtt ccttaaatag ggacctgtat gaatggctcc 2640 acgagggttc agctgtctct tacttttaac cagtgaaatt gacctgcccg tgaagaggcg 2700 ggcataacac agcaagacga gaagacccta tggagcttta atttattaat gcaaacagta 2760 cctaacaaac ccacaggtcc taaactacca aacctgcatt aaaaatttcg gttggggcga 2820 cctcggagca gaacccaacc tccgagcagt acatgctaag acttcaccag tcaaagcgaa 2880 ctactatact caattgatcc aataacttga ccaacggaac aagttaccct agggataaca 2940 gcgcaatcct attctagagt ccatatcaac aatagggttt acgacctcga tgttggatca 3000 ggacatcccg atggtgcagc cgctattaaa ggttcgtttg ttcaacgatt aaagtcctac 3060 gtgatctgag ttcagaccgg agtaatccag gtcggtttct atctacttca aattcctccc 3120 tgtacgaaag gacaagagaa ataaggccta cttcacaaag cgccttcccc cgtaaatgat 3180 atcatctcaa cttagtatta tacccacacc cacccaagaa cagggtttgt taagatggca 3240 gagcccggta atcgcataaa acttaaaact ttacagtcag aggttcaatt cctcttctta 3300 acaacatacc catggccaac ctcctactcc tcattgtacc cattctaatc gcaatggcat 3360 tcctaatgct taccgaacga aaaattctag gctatataca actacgcaaa ggccccaacg 3420 ttgtaggccc ctacgggcta ctacaaccct tcgctgacgc cataaaactc ttcaccaaag 3480 agcccctaaa acccgccaca tctaccatca ccctctacat caccgccccg accttagctc 3540 tcaccatcgc tcttctacta tgaacccccc tccccatacc caaccccctg gtcaacctca 3600 acctaggcct cctatttatt ctagccacct ctagcctagc cgtttactca atcctctgat 3660 cagggtgagc atcaaactca aactacgccc tgatcggcgc actgcgagca gtagcccaaa 3720 caatctcata tgaagtcacc ctagccatca ttctactatc aacattacta ataagtggct 3780 cctttaacct ctccaccctt atcacaacac aagaacacct ctgattactc ctgccatcat 3840 gacccttggc cataatatga tttatctcca cactagcaga gaccaaccga acccccttcg 3900 accttgccga aggggagtcc gaactagtct caggcttcaa catcgaatac gccgcaggcc 3960 ccttcgccct attcttcata gccgaataca caaacattat tataataaac accctcacca 4020 ctacaatctt cctaggaaca acatatgacg cactctcccc tgaactctac acaacatatt 4080 ttgtcaccaa gaccctactt ctaacctccc tgttcttatg aattcgaaca gcataccccc 4140 gattccgcta cgaccaactc atacacctcc tatgaaaaaa cttcctacca ctcaccctag 4200 cattacttat atgatatgtc tccataccca ttacaatctc cagcattccc cctcaaacct 4260 aagaaatatg tctgataaaa gagttacttt gatagagtaa ataataggag cttaaacccc 4320 cttatttcta ggactatgag aatcgaaccc atccctgaga atccaaaatt ctccgtgcca 4380 cctatcacac cccatcctaa agtaaggtca gctaaataag ctatcgggcc cataccccga 4440 aaatgttggt tatacccttc ccgtactaat taatcccctg gcccaacccg tcatctactc 4500 taccatcttt gcaggcacac tcatcacagc gctaagctcg cactgatttt ttacctgagt 4560 aggcctagaa ataaacatgc tagcttttat tccagttcta accaaaaaaa taaaccctcg 4620 ttccacagaa gctgccatca agtatttcct cacgcaagca accgcatcca taatccttct 4680 aatagctatc ctcttcaaca atatactctc cggacaatga accataacca atactaccaa 4740 tcaatactca tcattaataa tcataatagc tatagcaata aaactaggaa tagccccctt 4800 tcacttctga gtcccagagg ttacccaagg cacccctctg acatccggcc tgcttcttct 4860 cacatgacaa aaactagccc ccatctcaat catataccaa atctctccct cactaaacgt 4920 aagccttctc ctcactctct caatcttatc catcatagca ggcagttgag gtggattaaa 4980 ccaaacccag ctacgcaaaa tcttagcata ctcctcaatt acccacatag gatgaataat 5040 agcagttcta ccgtacaacc ctaacataac cattcttaat ttaactattt atattatcct 5100 aactactacc gcattcctac tactcaactt aaactccagc accacgaccc tactactatc 5160 tcgcacctga aacaagctaa catgactaac acccttaatt ccatccaccc tcctctccct 5220 aggaggcctg cccccgctaa ccggcttttt gcccaaatgg gccattatcg aagaattcac 5280 aaaaaacaat agcctcatca tccccaccat catagccacc atcaccctcc ttaacctcta 5340 cttctaccta cgcctaatct actccacctc aatcacacta ctccccatat ctaacaacgt 5400 aaaaataaaa tgacagtttg aacatacaaa acccacccca ttcctcccca cactcatcgc 5460 ccttaccacg ctactcctac ctatctcccc ttttatacta ataatcttat agaaatttag 5520 gttaaataca gaccaagagc cttcaaagcc ctcagtaagt tgcaatactt aatttctgta 5580 acagctaagg actgcaaaac cccactctgc atcaactgaa cgcaaatcag ccactttaat 5640 taagctaagc ccttactaga ccaatgggac ttaaacccac aaacacttag ttaacagcta 5700 agcaccctaa tcaactggct tcaatctact tctcccgccg ccgggaaaaa aggcgggaga 5760 agccccggca ggtttgaagc tgcttcttcg aatttgcaat tcaatatgaa aatcacctcg 5820 gagctggtaa aaagaggcct aacccctgtc tttagattta cagtccaatg cttcactcag 5880 ccattttacc tcacccccac tgatgttcgc cgaccgttga ctattctcta caaaccacaa 5940 agacattgga acactatacc tattattcgg cgcatgagct ggagtcctag gcacagctct 6000 aagcctcctt attcgagccg agctgggcca gccaggcaac cttctaggta acgaccacat 6060 ctacaacgtt atcgtcacag cccatgcatt tgtaataatc ttcttcatag taatacccat 6120 cataatcgga ggctttggca actgactagt tcccctaata atcggtgccc ccgatatggc 6180 gtttccccgc ataaacaaca taagcttctg actcttacct ccctctctcc tactcctgct 6240 cgcatctgct atagtggagg ccggagcagg aacaggttga acagtctacc ctcccttagc 6300 agggaactac tcccaccctg gagcctccgt agacctaacc atcttctcct tacacctagc 6360 aggtgtctcc tctatcttag gggccatcaa tttcatcaca acaattatca atataaaacc 6420 ccctgccata acccaatacc aaacgcccct cttcgtctga tccgtcctaa tcacagcagt 6480 cctacttctc ctatctctcc cagtcctagc tgctggcatc actatactac taacagaccg 6540 caacctcaac accaccttct tcgaccccgc cggaggagga gaccccattc tataccaaca 6600 cctattctga tttttcggtc accctgaagt ttatattctt atcctaccag gcttcggaat 6660 aatctcccat attgtaactt actactccgg aaaaaaagaa ccatttggat acataggtat 6720 ggtctgagct atgatatcaa ttggcttcct agggtttatc gtgtgagcac accatatatt 6780 tacagtagga atagacgtag acacacgagc atatttcacc tccgctacca taatcatcgc 6840 tatccccacc ggcgtcaaag tatttagctg actcgccaca ctccacggaa gcaatatgaa 6900 atgatctgct gcagtgctct gagccctagg attcatcttt cttttcaccg taggtggcct 6960 gactggcatt gtattagcaa actcatcact agacatcgta ctacacgaca cgtactacgt 7020 tgtagcccac ttccactatg tcctatcaat aggagctgta tttgccatca taggaggctt 7080 cattcactga tttcccctat tctcaggcta caccctagac caaacctacg ccaaaatcca 7140 tttcactatc atattcatcg gcgtaaatct aactttcttc ccacaacact ttctcggcct 7200 atccggaatg ccccgacgtt actcggacta ccccgatgca tacaccacat gaaacatcct 7260 atcatctgta ggctcattca tttctctaac agcagtaata ttaataattt tcatgatttg 7320 agaagccttc gcttcgaagc gaaaagtcct aatagtagaa gaaccctcca taaacctgga 7380 gtgactatat ggatgccccc caccctacca cacattcgaa gaacccgtat acataaaatc 7440 tagacaaaaa aggaaggaat cgaacccccc aaagctggtt tcaagccaac cccatggcct 7500 ccatgacttt ttcaaaaagg tattagaaaa accatttcat aactttgtca aagttaaatt 7560 ataggctaaa tcctatatat cttaatggca catgcagcgc aagtaggtct acaagacgct 7620 acttccccta tcatagaaga gcttatcacc tttcatgatc acgccctcat aatcattttc 7680 cttatctgct tcctagtcct gtatgccctt ttcctaacac tcacaacaaa actaactaat 7740 actaacatct cagacgctca ggaaatagaa accgtctgaa ctatcctgcc cgccatcatc 7800 ctagtcctca tcgccctccc atccctacgc atcctttaca taacagacga ggtcaacgat 7860 ccctccctta ccatcaaatc aattggccac caatggtact gaacctacga gtacaccgac 7920 tacggcggac taatcttcaa ctcctacata cttcccccat tattcctaga accaggcgac 7980 ctgcgactcc ttgacgttga caatcgagta gtactcccga ttgaagcccc cattcgtata 8040 ataattacat cacaagacgt cttgcactca tgagctgtcc ccacattagg cttaaaaaca 8100 gatgcaattc ccggacgtct aaaccaaacc actttcaccg ctacacgacc gggggtatac 8160 tacggtcaat gctctgaaat ctgtggagca aaccacagtt tcatgcccat cgtcctagaa 8220 ttaattcccc taaaaatctt tgaaataggg cccgtattta ccctatagca ccccctctac 8280 cccctctaga gcccactgta aagctaactt agcattaacc ttttaagtta aagattaaga 8340 gaaccaacac ctctttacag tgaaatgccc caactaaata ctaccgtatg gcccaccata 8400 attaccccca tactccttac actattcctc atcacccaac taaaaatatt aaacacaaac 8460 taccacctac ctccctcacc aaagcccata aaaataaaaa attataacaa accctgagaa 8520 ccaaaatgaa cgaaaatctg ttcgcttcat tcattgcccc cacaatccta ggcctacccg 8580 ccgcagtact gatcattcta tttccccctc tattgatccc cacctccaaa tatctcatca 8640 acaaccgact aatcaccacc caacaatgac taatcaaact aacctcaaaa caaatgataa 8700 ccatacacaa cactaaagga cgaacctgat ctcttatact agtatcctta atcattttta 8760 ttgccacaac taacctcctc ggactcctgc ctcactcatt tacaccaacc acccaactat 8820 ctataaacct agccatggcc atccccttat gagcgggcac agtgattata ggctttcgct 8880 ctaagattaa aaatgcccta gcccacttct taccacaagg cacacctaca ccccttatcc 8940 ccatactagt tattatcgaa accatcagcc tactcattca accaatagcc ctggccgtac 9000 gcctaaccgc taacattact gcaggccacc tactcatgca cctaattgga agcgccaccc 9060 tagcaatatc aaccattaac cttccctcta cacttatcat cttcacaatt ctaattctac 9120 tgactatcct agaaatcgct gtcgccttaa tccaagccta cgttttcaca cttctagtaa 9180 gcctctacct gcacgacaac acataatgac ccaccaatca catgcctatc atatagtaaa 9240 acccagccca tgacccctaa caggggccct ctcagccctc ctaatgacct ccggcctagc 9300 catgtgattt cacttccact ccataacgct cctcatacta ggcctactaa ccaacacact 9360 aaccatatac caatgatggc gcgatgtaac acgagaaagc acataccaag gccaccacac 9420 accacctgtc caaaaaggcc ttcgatacgg gataatccta tttattacct cagaagtttt 9480 tttcttcgca ggatttttct gagcctttta ccactccagc ctagccccta ccccccaatt 9540 aggagggcac tggcccccaa caggcatcac cccgctaaat cccctagaag tcccactcct 9600 aaacacatcc gtattactcg catcaggagt atcaatcacc tgagctcacc atagtctaat 9660 agaaaacaac cgaaaccaaa taattcaagc actgcttatt acaattttac tgggtctcta 9720 ttttaccctc ctacaagcct cagagtactt cgagtctccc ttcaccattt ccgacggcat 9780 ctacggctca acattttttg tagccacagg cttccacgga cttcacgtca ttattggctc 9840 aactttcctc actatctgct tcatccgcca actaatattt cactttacat ccaaacatca 9900 ctttggcttc gaagccgccg cctgatactg gcattttgta gatgtggttt gactatttct 9960 gtatgtctcc atctattgat gagggtctta ctcttttagt ataaatagta ccgttaactt 10020 ccaattaact agttttgaca acattcaaaa aagagtaata aacttcgcct taattttaat 10080 aatcaacacc ctcctagcct tactactaat aattattaca ttttgactac cacaactcaa 10140 cggctacata gaaaaatcca ccccttacga gtgcggcttc gaccctatat cccccgcccg 10200 cgtccctttc tccataaaat tcttcttagt agctattacc ttcttattat ttgatctaga 10260 aattgccctc cttttacccc taccatgagc cctacaaaca actaacctgc cactaatagt 10320 tatgtcatcc ctcttattaa tcatcatcct agccctaagt ctggcctatg agtgactaca 10380 aaaaggatta gactgaaccg aattggtata tagtttaaac aaaacgaatg atttcgactc 10440 attaaattat gataatcata tttaccaaat gcccctcatt tacataaata ttatactagc 10500 atttaccatc tcacttctag gaatactagt atatcgctca cacctcatat cctccctact 10560 atgcctagaa ggaataatac tatcgctgtt cattatagct actctcataa ccctcaacac 10620 ccactccctc ttagccaata ttgtgcctat tgccatacta gtctttgccg cctgcgaagc 10680 agcggtgggc ctagccctac tagtctcaat ctccaacaca tatggcctag actacgtaca 10740 taacctaaac ctactccaat gctaaaacta atcgtcccaa caattatatt actaccactg 10800 acatgacttt ccaaaaaaca cataatttga atcaacacaa ccacccacag cctaattatt 10860 agcatcatcc ctctactatt ttttaaccaa atcaacaaca acctatttag ctgttcccca 10920 accttttcct ccgaccccct aacaaccccc ctcctaatac taactacctg actcctaccc 10980 ctcacaatca tggcaagcca acgccactta tccagtgaac cactatcacg aaaaaaactc 11040 tacctctcta tactaatctc cctacaaatc tccttaatta taacattcac agccacagaa 11100 ctaatcatat tttatatctt cttcgaaacc acacttatcc ccaccttggc tatcatcacc 11160 cgatgaggca accagccaga acgcctgaac gcaggcacat acttcctatt ctacacccta 11220 gtaggctccc ttcccctact catcgcacta atttacactc acaacaccct aggctcacta 11280 aacattctac tactcactct cactgcccaa gaactatcaa actcctgagc caacaactta 11340 atatgactag cttacacaat agcttttata gtaaagatac ctctttacgg actccactta 11400 tgactcccta aagcccatgt cgaagccccc atcgctgggt caatagtact tgccgcagta 11460 ctcttaaaac taggcggcta tggtataata cgcctcacac tcattctcaa ccccctgaca 11520 aaacacatag cctacccctt ccttgtacta tccctatgag gcataattat aacaagctcc 11580 atctgcctac gacaaacaga cctaaaatcg ctcattgcat actcttcaat cagccacata 11640 gccctcgtag taacagccat tctcatccaa accccctgaa gcttcaccgg cgcagtcatt 11700 ctcataatcg cccacgggct tacatcctca ttactattct gcctagcaaa ctcaaactac 11760 gaacgcactc acagtcgcat cataatcctc tctcaaggac ttcaaactct actcccacta 11820 atagcttttt gatgacttct agcaagcctc gctaacctcg ccttaccccc cactattaac 11880 ctactgggag aactctctgt gctagtaacc acgttctcct gatcaaatat cactctccta 11940 cttacaggac tcaacatact agtcacagcc ctatactccc tctacatatt taccacaaca 12000 caatggggct cactcaccca ccacattaac aacataaaac cctcattcac acgagaaaac 12060 accctcatgt tcatacacct atcccccatt ctcctcctat ccctcaaccc cgacatcatt 12120 accgggtttt cctcttgtaa atatagttta accaaaacat cagattgtga atctgacaac 12180 agaggcttac gaccccttat ttaccgagaa agctcacaag aactgctaac tcatgccccc 12240 atgtctaaca acatggcttt ctcaactttt aaaggataac agctatccat tggtcttagg 12300 ccccaaaaat tttggtgcaa ctccaaataa aagtaataac catgcacact actataacca 12360 ccctaaccct gacttcccta attcccccca tccttaccac cctcgttaac cctaacaaaa 12420 aaaactcata cccccattat gtaaaatcca ttgtcgcatc cacctttatt atcagtctct 12480 tccccacaac aatattcatg tgcctagacc aagaagttat tatctcgaac tgacactgag 12540 ccacaaccca aacaacccag ctctccctaa gcttcaaact agactacttc tccataatat 12600 tcatccctgt agcattgttc gttacatggt ccatcataga attctcactg tgatatataa 12660 actcagaccc aaacattaat cagttcttca aatatctact catcttccta attaccatac 12720 taatcttagt taccgctaac aacctattcc aactgttcat cggctgagag ggcgtaggaa 12780 ttatatcctt cttgctcatc agttgatgat acgcccgagc agatgccaac acagcagcca 12840 ttcaagcaat cctatacaac cgtatcggcg atatcggttt catcctcgcc ttagcatgat 12900 ttatcctaca ctccaactca tgagacccac aacaaatagc ccttctaaac gctaatccaa 12960 gcctcacccc actactaggc ctcctcctag cagcagcagg caaatcagcc caattaggtc 13020 tccacccctg actcccctca gccatagaag gccccacccc agtctcagcc ctactccact 13080 caagcactat agttgtagca ggaatcttct tactcatccg cttccacccc ctagcagaaa 13140 atagcccact aatccaaact ctaacactat gcttaggcgc tatcaccact ctgttcgcag 13200 cagtctgcgc ccttacacaa aatgacatca aaaaaatcgt agccttctcc acttcaagtc 13260 aactaggact cataatagtt acaatcggca tcaaccaacc acacctagca ttcctgcaca 13320 tctgtaccca cgccttcttc aaagccatac tatttatgtg ctccgggtcc atcatccaca 13380 accttaacaa tgaacaagat attcgaaaaa taggaggact actcaaaacc atacctctca 13440 cttcaacctc cctcaccatt ggcagcctag cattagcagg aatacctttc ctcacaggtt 13500 tctactccaa agaccacatc atcgaaaccg caaacatatc atacacaaac gcctgagccc 13560 tatctattac tctcatcgct acctccctga caagcgccta tagcactcga ataattcttc 13620 tcaccctaac aggtcaacct cgcttcccca cccttactaa cattaacgaa aataacccca 13680 ccctactaaa ccccattaaa cgcctggcag ccggaagcct attcgcagga tttctcatta 13740 ctaacaacat ttcccccgca tcccccttcc aaacaacaat ccccctctac ctaaaactca 13800 cagccctcgc tgtcactttc ctaggacttc taacagccct agacctcaac tacctaacca 13860 acaaacttaa aataaaatcc ccactatgca cattttattt ctccaacata ctcggattct 13920 accctagcat cacacaccgc acaatcccct atctaggcct tcttacgagc caaaacctgc 13980 ccctactcct cctagaccta acctgactag aaaagctatt acctaaaaca atttcacagc 14040 accaaatctc cacctccatc atcacctcaa cccaaaaagg cataattaaa ctttacttcc 14100 tctctttctt cttcccactc atcctaaccc tactcctaat cacataacct attcccccga 14160 gcaatctcaa ttacaatata tacaccaaca aacaatgttc aaccagtaac tactactaat 14220 caacgcccat aatcatacaa agcccccgca ccaataggat cctcccgaat caaccctgac 14280 ccctctcctt cataaattat tcagcttcct acactattaa agtttaccac aaccaccacc 14340 ccatcatact ctttcaccca cagcaccaat cctacctcca tcgctaaccc cactaaaaca 14400 ctcaccaaga cctcaacccc tgacccccat gcctcaggat actcctcaat agccatcgct 14460 gtagtatatc caaagacaac catcattccc cctaaataaa ttaaaaaaac tattaaaccc 14520 atataacctc ccccaaaatt cagaataata acacacccga ccacaccgct aacaatcaat 14580 actaaacccc cataaatagg agaaggctta gaagaaaacc ccacaaaccc cattactaaa 14640 cccacactca acagaaacaa agcatacatc attattctcg cacggactac aaccacgacc 14700 aatgatatga aaaaccatcg ttgtatttca actacaagaa caccaatgac cccaatacgc 14760 aaaactaacc ccctaataaa attaattaac cactcattca tcgacctccc caccccatcc 14820 aacatctccg catgatgaaa cttcggctca ctccttggcg cctgcctgat cctccaaatc 14880 accacaggac tattcctagc catgcactac tcaccagacg cctcaaccgc cttttcatca 14940 atcgcccaca tcactcgaga cgtaaattat ggctgaatca tccgctacct tcacgccaat 15000 ggcgcctcaa tattctttat ctgcctcttc ctacacatcg ggcgaggcct atattacgga 15060 tcatttctct actcagaaac ctgaaacatc ggcattatcc tcctgcttgc aactatagca 15120 acagccttca taggctatgt cctcccgtga ggccaaatat cattctgagg ggccacagta 15180 attacaaact tactatccgc catcccatac attgggacag acctagttca atgaatctga 15240 ggaggctact cagtagacag tcccaccctc acacgattct ttacctttca cttcatcttg 15300 cccttcatta ttgcagccct agcaacactc cacctcctat tcttgcacga aacgggatca 15360 aacaaccccc taggaatcac ctcccattcc gataaaatca ccttccaccc ttactacaca 15420 atcaaagacg ccctcggctt acttctcttc cttctctcct taatgacatt aacactattc 15480 tcaccagacc tcctaggcga cccagacaat tataccctag ccaacccctt aaacacccct 15540 ccccacatca agcccgaatg atatttccta ttcgcctaca caattctccg atccgtccct 15600 aacaaactag gaggcgtcct tgccctatta ctatccatcc tcatcctagc aataatcccc 15660 atcctccata tatccaaaca acaaagcata atatttcgcc cactaagcca atcactttat 15720 tgactcctag ccgcagacct cctcattcta acctgaatcg gaggacaacc agtaagctac 15780 ccttttacca tcattggaca agtagcatcc gtactatact tcacaacaat cctaatccta 15840 ataccaacta tctccctaat tgaaaacaaa atactcaaat gggcctgtcc ttgtagtata 15900 aactaataca ccagtcttgt aaaccggaga tgaaaacctt tttccaagga caaatcagag 15960 aaaaagtctt taactccacc attagcaccc aaagctaaga ttctaattta aactattctc 16020 tgttctttca tggggaagca gatttgggta ccacccaagt attgactcac ccatcaacaa 16080 ccgctatgta tttcgtacat tactgccagc caccatgaat attgtacggt accataaata 16140 cttgaccacc tgtagtacat aaaaacccaa tccacatcaa aaccccctcc ccatgcttac 16200 aagcaagtac agcaatcaac cctcaactat cacacatcaa ctgcaactcc aaagccaccc 16260 ctcacccact aggataccaa caaacctacc cacccttaac agtacatagt acataaagcc 16320 atttaccgta catagcacat tacagtcaaa tcccttctcg tccccatgga tgacccccct 16380 cagatagggg tcccttgacc accatcctcc gtgaaatcaa tatcccgcac aagagtgcta 16440 ctctcctcgc tccgggccca taacacttgg gggtagctaa agtgaactgt atccgacatc 16500 tggttcctac ttcagggtca taaagcctaa atagcccaca cgttcccctt aaataagaca 16560 tcacgatg 16568 2 23 DNA Homo sapiens 2 gtatttggat gtcagaaaca ctt 23 3 19 DNA Homo sapiens 3 acttcagggt cataaagcc 19 4 23 DNA Homo sapiens 4 gtatttggat gtcagaaaca ctt 23 5 19 DNA Homo sapiens 5 acttcagggc cataaagcc 19 6 21 DNA Homo sapiens 6 acccgcgtcc gcgccatggc c 21 7 21 DNA Homo sapiens 7 acccgcgtcc tcgccatggc c 21 8 8 DNA Homo sapiens 8 taaccata 8 9 9 DNA Homo sapiens 9 tctcttacc 9 10 10 DNA Homo sapiens 10 cacactacta 10 11 9 DNA Homo sapiens 11 tttaaccag 9 

1. A method of monitoring exposure of a person to an environmental pollutant, comprising the step of: determining at two or more time points the presence of one or more mutations in mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant; comparing the amount of mutations in mtDNA at different time points, wherein the amount of mutations correlates with amount of exposure to the environmental pollutant.
 2. A method of monitoring exposure of a person to an environmental pollutant, comprising the step of: measuring prevalence of one or more mutations in mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant, wherein a measured prevalence of one or more mutations in mtDNA of greater than 1% indicates clonal expansion of cells which harbor the one or more mutations in the person.
 3. A method of monitoring exposure of a person to an environmental pollutant, comprising the step of: measuring one or more mutations in a D-loop of mitochondrial DNA (mtDNA) in a body fluid of a person exposed to an environmental pollutant, wherein the number of mutations in mtDNA correlates with exposure to the environmental pollutant.
 4. The method of claim 1, 2, or 3 wherein the body fluid is urine.
 5. The method of claim 1, 2, or 3 wherein the body fluid is saliva.
 6. The method of claim 1, 2, or 3 wherein the body fluid is sputum.
 7. The method of claim 1, 2, or 3 wherein the body fluid is brouchoalveolar lavage.
 8. The method of claim 1, 2, or 3 wherein mutations in mtDNA are measured with reference to mtDNA isolated from a normal tissue of the human.
 9. The method of claim 8 wherein the normal tissue is paraffin-embedded.
 10. The method of claim 1, 2, or 3 wherein mutations in mtDNA are measured with reference to mtDNA isolated from a blood, serum, or plasma sample of the human.
 11. The method or claim 1 or 2 wherein mutations in mtDNA are measured by analysis of a gene encoding NADH dehydrogenase
 4. 12. The method of claim 1 or 2 wherein mutations in mtDNA are measured by analysis of a gene encoding 16S rRNA.
 13. The method of claim 2 wherein prevalence of one or more mutations in mtDNA in the body fluid is measured over time, whereby clonal expansion of cells can be monitored.
 14. The method of claim 1 or 2 wherein mutations in mtDNA are measured by analysis of a cytochrome b gene.
 15. The method of claim 1, 2, or 3 wherein the mutated mtDNA is found to bear a silent mutation.
 16. The method of claim 1 or 2 wherein the mutated mtDNA is measured by analysis of non-coding regions.
 17. The method of claim 1, 2, or 3 wherein the mutated mtDNA is measured by amplifying mtDNA segments of about 10 bp to about 4 kb.
 18. The method of claim 1, 2, or 3 wherein the mutated mtDNA is measured by amplifying mtDNA segments of about 10 bp to about 2 kb.
 19. The method of claim 1, 2, or 3 wherein the mutated mtDNA is measured by amplifying mtDNA segments of about 2 kb to about 4 kb.
 20. The method of claim 1, 2, or 3 wherein the mutated mtDNA is measured by an oligonucleotide mismatch ligation assay.
 21. The method of claim 1, 2, or 3 wherein the environmental pollutant is cigarette smoke.
 22. The method of claim 1, 2, or 3 wherein the environmental pollutant is a biological toxin.
 23. The method of claim 1, 2, or 3 wherein the environmental pollutant is radiation.
 24. The method of claim 1, 2, or 3 wherein the environmental pollutant is industrial waste.
 25. The method of claim 1, 2, or 3 wherein the environmental pollutant is chemical.
 26. The method of claim 1, 2, or 3 wherein the environmental pollutant is water-borne.
 27. The method of claim 1, 2, or 3 wherein the environmental pollutant is air-borne.
 28. The method of claim 1, 2, or 3 wherein the environmental pollutant is a drug.
 29. A kit for monitoring exposure of a person to environmental pollutants, comprising: one or more primers which hybridize to a mitochondrial D-loop for making a primer extension product; and written material identifying mutations which are found in the D-loop as a result of exposure to one or more environmental pollutants.
 30. The kit of claim 29 further comprising a buffer.
 31. The kit of claim 29 further comprising nucleic acid probes for hybridization to the extension product.
 32. The kit of claim 29 wherein the primers are for PCR.
 33. The kit of claim 29 wherein the primers are for a ligation assay.
 34. The method of claim 3 wherein the mutation is selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; and A→G at nucleotide
 16300. 35. The kit of claim 29 wherein the written material identifies a mutation selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; and A→G at nucleotide
 16300. 36. The method of claim 11 wherein the mutation is selected from the group consisting of: A→G at nucleotide 10792, C→T at nucleotide 10793, C→T at nucleotide 10822, A→G at nucleotide 10978, A→G at nucleotide 11065, G→A at nucleotide 11518, C→T at nucleotide 12049, T→C at nucleotide 10966, and G→A at nucleotide
 11150. 37. The method of claim 12 wherein the mutation is selected from the group consisting of: G→A at nucleotide 2056, T→C at nucleotide 2445, T→C at nucleotide 2664, and G→A at nucleotide
 3054. 38. The method of claim 14 wherein the mutation is Δ7 amino acids at nucleotide
 15642. 39. An oligonucleotide probe comprising a sequence of at least 10 contiguous nucleotides of a human mitochondrial genome, wherein the oligonucleotide comprises a mutation selected from the group consisting of: a mutation selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793; C→T at nucleotide 10822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; G→A at nucleotide 3054; T→C substitution at position 710; T→C substitution at position 1738; T→C substitution at position 3308; G→A substitution at position 8009; G→A substitution at position 14985; T→C substitution at position 15572; G→A substitution at position 9949; T→C substitution at position 10563; G→A substitution at position 6264; A insertion at position.12418; T→C substitution at position 1967; and T→A substitution at position
 2299. 40. An oligonucleotide primer comprising a sequence of at least 10 contiguous nucleotides of a human mitochondrial genome, wherein the oligonucleotide comprises a mutation selected from the group consisting of: a mutation selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793: C→T at nucleotide 1 0822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; G→A at nucleotide 3054;T→C substitution at position 710; T→C substitution at position 1738; T→C substitution at position 3308; G→A substitution at position 8009; G→A substitution at position 14985; T→C substitution at position 15572; G→A substitution at position 9949; T→C substitution at position 10563; G→A substitution at position 6264; A insertion at position 1241 8; T→C substitution at position 1967; and T→A substitution at position
 2299. 41. A method to aid in detecting the presence of tumor cells in a patient, comprising: determining the presence of a single basepair mutation in a mitochondrial genome of a cell sample of a patient, wherein the mutation is found in a tumor of the patient but not in normal tissue of the patient, wherein the tumor is not a colorectal tumor; and identifying the patient as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.
 42. A method to aid in detecting the presence of tumor cells in a patient, comprising: determining the presence of a mutation in a D-loop of a mitochondrial genome of a cell sample of a patient, wherein the mutation is found in a tumor of the patient but not in normal tissue of the patient; and identifying the patient as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.
 43. The method of claim 42 wherein the mutation is selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; and A→G at nucleotide
 16300. 44. A method to aid in detecting the presence of tumor cells in a patient, comprising: determining the presence of a single basepair mutation in a mitochondrial genome of a cell sample of a patient, wherein the mutation is found in a cancer of the patient but not in normal tissue of the patient, wherein the cancer is selected from the group of cancers consisting of: lung, head and neck, bladder, brain, breast, lymphoma, leukaemia, skin, prostate, stomach, pancreas, liver, ovarian, uterine, testicular, and bone; and identifying the patient as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.
 45. A method to aid in detecting the presence of tumor cells in a patient, comprising: step for determining the presence of a single basepair mutation in a mitochondrial genome of a cell sample of a patient, wherein the mutation is found in a tumor of the patient but not in normal tissue of the patient, wherein the cancer is selected from the group of cancers consisting of: lung, head and neck, and bladder; and identifying the patient as having a tumor if one or more single basepair mutations are determined in the mitochondrial genome of the cell sample of the patient.
 46. A method to aid in detecting the presence of tumor cells in a patient, comprising: determining the presence of a mutation in a mitochondrial genome of a cell sample of a patient, wherein the mutation is selected from the group consisting of: T→C at nucleotide 114; ΔC at nucleotide 302; C→A at nucleotide 386; insert T at nucleotide 16189; A→C at nucleotide 16265; A→T at nucleotide 16532; C→T at nucleotide 150; T→C at nucleotide 195; ΔC at nucleotide 302; C→A at nucleotide 16183; C→T at nucleotide 16187; T→C at nucleotide 16519; G→A at nucleotide 16380; G→A at nucleotide 75; insert C at nucleotide 302; insert CG at nucleotide 514; T→C at nucleotide 16172; C→T at nucleotide 16292; A→G at nucleotide 16300; A→G at nucleotide 10792; C→T at nucleotide 10793; C→T at nucleotide 10822; A→G at nucleotide 10978; A→G at nucleotide 11065; G→A at nucleotide 11518; C→T at nucleotide 12049; T→C at nucleotide 10966; G→A at nucleotide 11150; G→A at nucleotide 2056; T→C at nucleotide 2445; T→C at nucleotide 2664; T→C at nucleotide 10071; T→C at nucleotide 10321; T→C at nucleotide 12519; Δ7 amino acids at nucleotide 15642; G→A at nucleotide 5521; G→A at nucleotide 12345; and G→A at nucleotide 3054; and identifying the patient as having a tumor if one or more mutations are determined in the mitochondrial genome of the cell sample of the patient.
 47. The method of claim 41, 42, 44, 45, or 46 wherein the cell sample is from blood.
 48. The method of claim 41, 42, 44, 45, or 46 wherein the cell sample is from urine.
 49. The method of claim 41, 42, 44, 45, or 46 wherein the cell sample is from sputum.
 50. The method of claim 41, 42, 44, 45, or 46 wherein the cell sample is from saliva.
 51. The method of claim 41, 42, 44, 45, or 46 wherein the cell sample is from feces.
 52. The method of claim 41, 42, 44, 45, or 46 wherein the step for determining comprises amplifying mitochondrial DNA.
 53. The method of claim 41, 42, 44, 45, or 46 wherein the step for determining comprises sequencing mitochondrial DNA.
 54. The method of claim 41, 42, 44, 45, or 46 wherein the step for determining comprises hybridization of DNA amplified from the mitochondrial genome of the cell sample to an array of oligonucleotides which comprises matched and mismatched sequences to human mitochondrial genomic DNA.
 55. The method of claim 41, 42, 44, 45, or 46 wherein the mutation is a substitution mutation.
 56. The method of claim 41, 42, 44, 45, or 46 wherein the mutation is a one basepair insertion.
 57. The method of claim 41, 42, 44, 45, or 46 wherein the mutation is a one basepair deletion.
 58. The method of claim 41, 42, 44, 45, or 46 wherein the mutation is a transition mutation.
 59. The method of claim 41, 42, 44, 45, or 46 wherein the mutation is a homoplasmic mutation.
 60. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 710. 61. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 1738. 62. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 3308. 63. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A substitution at position
 8009. 64. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A substitution at position
 14985. 65. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 15572. 66. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A substitution at position
 9949. 67. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 10563. 68. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A substitution at position
 6264. 69. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an A insertion at position
 12418. 70. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C substitution at position
 1967. 71. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→A substitution at position
 2299. 72. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 10071. 73. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 10321. 74. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 12519. 75. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 5521. 76. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 12345. 77. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 114. 78. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a ΔC at nucleotide
 302. 79. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→A at nucleotide
 386. 80. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an insert T at nucleotide
 16189. 81. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a A→C at nucleotide
 16265. 82. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a A→T at nucleotide
 16532. 83. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 150. 84. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 195. 85. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a ΔC at nucleotide
 302. 86. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→A at nucleotide
 16183. 87. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 16187. 88. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 16519. 89. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 16380. 90. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide 75
 91. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an insert C at nucleotide
 302. 92. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an insert CG at nucleotide
 514. 93. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 16172. 94. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 16292. 95. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an A→G at nucleotide
 16300. 96. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is an A→G at nucleotide
 10792. 97. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 10793. 98. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 10822. 99. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a A→G at nucleotide
 10978. 100. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a A→G at nucleotide
 11065. 101. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 11518. 102. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a C→T at nucleotide
 12049. 103. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 10966. 104. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 11150. 105. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 2056. 106. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 2445. 107. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 2664. 108. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 10071. 109. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 10321. 110. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a T→C at nucleotide
 12519. 111. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a Δ7 amino acids at nucleotide
 15642. 112. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 5521. 113. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 12345. 114. The oligonucleotide probe of claim 39 or primer of claim 40 wherein the mutation is a G→A at nucleotide
 3054. 115. The method of claim 2 wherein the mutation was identified previously in a tumor of the patient.
 116. The method of claim 115 wherein the patient has received anti-cancer therapy and the step for determining is performed at least three times to monitor progress of the anti-cancer therapy.
 117. The method of claim 1 further comprising a step for testing a normal tissue of the patient to determine the absence of the mutation. 